Re: [PATCH V2 1/3] scsi: mptxsas: try 64 bit DMA when 32 bit DMA fails

From: Timur Tabi
Date: Tue Nov 10 2015 - 12:01:08 EST

On 11/10/2015 10:47 AM, Arnd Bergmann wrote:
What BenH was worried about here is that the driver sets different masks
for streaming and coherent mappings, which is indeed a worry that
could hit us on ARM as well, but I suppose we'll have to deal with
that in platform code.

Setting both masks to 32-bit is something that a lot of drivers do,
and without IOMMU enabled, you'd hit the same bug on all of them.

Also note that I think that on PowerPC, the mask is set to 32 by default for all devices. I don't think we do that on ARM64. So on PowerPC, some drivers get away with not explicitly setting the mask.

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